Abstract
Auxetic mechanical metamaterials are engineered systems that exhibit the unusual macroscopic property of a negative Poisson's ratio due to sub-unit structure rather than chemical composition. Although their unique behaviour makes them superior to conventional materials in many practical applications, they are limited in availability. Here, we propose a new class of hierarchical auxetics based on the rotating rigid units mechanism. These systems retain the enhanced properties from having a negative Poisson's ratio with the added benefits of being a hierarchical system. Using simulations on typical hierarchical multi-level rotating squares, we show that, through design, one can control the extent of auxeticity, degree of aperture and size of the different pores in the system. This makes the system more versatile than similar non-hierarchical ones, making them promising candidates for industrial and biomedical applications, such as stents and skin grafts.
Highlights
Auxetic mechanical metamaterials are engineered systems that exhibit the unusual macroscopic property of a negative Poisson’s ratio due to sub-unit structure rather than chemical composition
Despite extensive studies on rotating rigid units and their role in generating auxetic behaviour in various classes of materials such as foams[20,21], silicates[22,23,24] and zeolites[25,26], no hierarchical auxetic system based on this concept has as yet been identified
Such hierarchical auxetic systems are expected to provide a new impetus in the design of superior auxetics given the well-known auxetic capabilities of rotating rigid unit mechanisms as well as the superior properties arising from hierarchy
Summary
Ruben Gatt[1], Luke Mizzi[1], Joseph I. We propose a new class of hierarchical auxetics based on the rotating rigid units mechanism These systems retain the enhanced properties from having a negative Poisson’s ratio with the added benefits of being a hierarchical system. Despite extensive studies on rotating rigid units and their role in generating auxetic behaviour in various classes of materials such as foams[20,21], silicates[22,23,24] and zeolites[25,26], no hierarchical auxetic system based on this concept has as yet been identified Such hierarchical auxetic systems are expected to provide a new impetus in the design of superior auxetics given the well-known auxetic capabilities of rotating rigid unit mechanisms as well as the superior properties arising from hierarchy. These sub-units are connected from vertices which are nearest of these corners, with the net effect that the connectivity at Level 1 is best described by the equivalent of a Type Ib ‘rotating parallelograms’ system[28], or in some cases, the Type I connected rectangles, depending on the angles between the Level 1 sub-units
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have